Facile synthesis of Ag/Co3O4 nanocubes for on-demand H2 evolution upon dimethylamine borane hydrolysis

摘要

The crystalline structure and morphology of heterogeneous catalysts plays an increasingly important role in its ultimate catalytic activity. Herein, we have synthesized and compared the catalytic activities of Ag/Co3O4 cubes (Ag/Co3O4-c), Ag/Co3O4 octahedron (Ag/Co3O4-o) and Ag/Co3O4 truncated octahedron (Ag/Co3O4-t), via immobilization of Ag nanoparticles onto the surface of Co3O4-c/o/t, in dimethylamine borane (DB) hydrolysis for on-demand H-2 evolution at 30 degrees C. In particular, Co3O4-c, Co3O4-o and Co3O4-t were enclosed with six {100}, six {111} resp. the mixture of six {100} and eight {111} exposing facets. Ag/Co3O4-c (1373 mol (H-2)center dot mol(Ag)(-1)center dot h(-1)) exhibited more efficient catalytic activity than those of Ag/Co3O4-t (1172 mol (H-2)center dot mol(Ag)(-1)center dot h(-1)) and Ag/Co3O4-o (804 mol (H-2)center dot mol(Ag)(-1)center dot h(-1)) in DB hydrolysis. The (Density Functional Theory) DFT result illustrated that the Eads of Ag/Co3O4 {100} facets (-2.07 eV) was much lower than that of Ag/Co3O4 {111} facets (-1.72 eV), suggesting Ag/Co3O4 {100} facets is favor of DB adsorption, which is in consistent with our above experimental result. More interestingly, "on-off" control of on-demand H-2 evolution upon DB hydrolysis over Ag/Co3O4-c was successfully achieved by the Zn2+/EDTA-2Na system, for effectively and safely producing, transporting and storing hydrogen in the future.

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